Time rules our lives. From the rising and setting of the sun to the cycles of nature, the thought processes in our brains, and the biorhythms in our day, nothing so pervades our existence and yet is so difficult to explain. Time seems to be woven into the very fabric of the universe. But why?Lectures:1. Why Time Is a Mystery2. What Is Time?3. Keeping Time4. Time???s Arrow5. The Second Law of Thermodynamics6. Reversibility and the Laws of Physics7. Time Reversal in Particle Physics8. Time in Quantum Mechanics9. Entropy and Counting10. Playing with Entropy11. The Past Hypothesis12. Memory, Causality, and Action13. Boltzmann Brains14. Complexity and Life15. The Perception of Time16. Memory and Consciousness17. Time and Relativity18. Curved Spacetime and Black Holes19. Time Travel20. Black Hole Entropy21. Evolution of the Universe22. The Big Bang23. The Multiverse24. Approaches to the Arrow of Time